bug#57066: 29.0.50; Complex emoji overlaps with text

[Eli Zaretskii]

> Date: Thu, 11 Aug 2022 16:23:47 +0900
> From: YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>
> Cc:   info@protesilaos.com,
>       57066@debbugs.gnu.org
> 
> On Thu, 11 Aug 2022 15:49:10 +0900,
> Eli Zaretskii wrote:
> > 
> > Do other font backends that use HarfBuzz need something similar, or is
> > this specific to the ftcrhb backend?
> 
> The xfthb font backend driver does not need the similar change since
> it always uses 1.0 / (1 << 6) as the position unit, just like the
> patched ftcrhb code for HarfBuzz 5 and later.
> 
> I'm not familiar with the harfbuzz driver on W32.  But at least, the
> bug#489 on HarfBuzz is about hb-ft.cc.  So probably the
> uniscribe-specific part is not affected.

OK, thanks.

I think the fix should be installed on the emacs-28 release branch.
It seems to be quite safe.  Do you agree?